Telephone-exchange system.



PATENTED MAY 26. 1908.

E. E. GORWIN. TELEPHONE EXEEANEE SYSTEM.

APPLICATION FILED OUT. 1, 1906.

jimmy? flax/a2? co., WASHINGTON, n. c.

IINITED srarawr rric ELMER R. CORWIN, OF CHICAGO, ILLINOIS, ASSIGNOR TO MONARCH TELEPHONE MANUFAC- TURING CO., A CORPORATION OF ILLINOIS.

TELEPHONE-EXCHANGE SYSTEM.

Specification of Letters Patent.

Patented May 26, 1908.

Application filed October 1, 1906. Serial No. 337,027.

T 0 all whom it may concern:

Be it known that I, ELMER R. CoRwIN, citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented a certain new and useful Improvement in Telephone-Exchange Systems, of which the following is a full, clear, concise, and exact description, reference be ing had to the accompanying drawings, forming a part of this specification.

My invention relates to telephone exchange systems, and has for one of its objects the provision of an improved circuit arrangement and apparatus for governing the operation of cut-off relays. In practicing this feature of my invention, I so dispose the cut-off relays that they are under the joint control of the subscribers and operators. By this arrangement improved and more simplified apparatus results, inasmuch as the cut-off relays are preferably permanently connected with the line and the circuits for the voice currents although having permanent connection with the sides of the telephone lines, need not be impaired by the association of the cut-off relays therewith. I desirably associate with each cut-off relay a line relay whose winding is subdivided into two coils, between which battery is connected, and employ cord connecting apparatus which, on account of its circuit connections and the circuit connections of the out off relay, is adapted to connect said cut-off relay in parallel with one of the windings of the line relay, so that preferably the impedance on each side of the battery may thereby become equal in order that the system may be balanced, said windings of the line relay themselves being of unequal resistance, preferably. The cut-ofl relay has one of its terminals connected between the line relay windings and the other terminal connected directly with one of said windings and separated from the other windings by means of a condenser, whereby the telephonic circuit may be rendered intact without the inclusion of unnecessary impedance and without impairing the oint control of the cut-off relay effected by each subscriber and operator. This condenser, in the preferred embodiment of the invention, also serves to separate the line and clearing-out circuits, this feature of the present system being covered by my Patent No. 827,787, dated August 7, 1906.

effected.

In practicing my invention, the common battery is included in series with the line relay, the circuit containing this battery and relay being governed by the sub-station switch-hook or other switch device, whose elements are serially included in circuit with 1 said battery and relay. The operator, upon making connection with a line does not disturb this relation of battery, line relay and substation switch-hook, although current for her apparatus is derived from the said battery. This result is secured by having her instrumentality or instrumentalities that are to receive such current, upon connecting a line with a cord circuit, included in series relation with the sub-station switch-hook and the battery.

Another object of my invention is to so construct a multiple switch-board system that calling subscribers lines cannot be tested as busy until connections have been effected at the exchange therewith; for example, let it be assumed that a telephone exchange system is equipped with telephone lines extending from sub-stations to an exchange and there provided each with a plurality of jacks in association with cord circuits having answering end connecting plugs. If a subscriber initiates a call, the thimbles of his jacks will not permit a busy test until either an answering plug or a connecting plug has been inserted in one of his acks. This feature of my invention is of advantage, since a calling subscriber may have interconnection with another subscriber calling him until the first calling subscriber has had telephonic connection established with his line at the exchange, either partially or com pletely.

I will explain my invention more fully by reference to the accompanying drawing, showing the preferred embodiment thereof, in which-- Figure 1 is a general view indicating atelephone exchange system including subscribers lines extending from sub-stations to an exchange and central apparatus whereby interconnection between subscribers may be Fig. 2 is a diagram indicating more simply certain characteristics of my improved circuits. Fig. 3 is a view somewhat in the nature of Fig. 2 but illustrating more of the apparatus than is illustrated in Fig. 1.

Like parts are indicated by similar characters of reference throughout the different figures.

There are indicated two of many substations, A, B, each, in the embodiment of the invention shown, having a transmitter 1, a receiver 2, a call bell 3, a switch-hook 4, a condenser 5, and an impedance coil 6, together with suitable contacts and circuit connections whereby, when the telephone receivers 2 are upon their switch-hooks, the bells 3, together with the condensers 5, are bridged across the sides of the telephone lines 7, 8, and whereby, when the telephone receivers are removed from their hooks, the bridges including said signal bells are opened and the transmitters are thrown into effective relation with the lines, whereby battery may be fed therethrough through the impedance coil 6, and whereby telephonic currents may be impressed upon the lines at the sub stations of the transmitters or may be received at the receivers. I do not wish to be limited to the precise sub-station circuits indicated, however. The limbs 7, S of the telephone lines are in multiple switchboard practice, multiplied to sleeve contacts 9 and tip contacts 10, respectively, of multiple spring jacks, though features of the inven tion may be used in connection with switchboards that are not multiple switch-boards, in which case but one jack need be supplied to a line. In multiple switch-board practice, one of the jacks may act as an answering jack, these answering jacks, as is understood, being suitably distributed among the difi'erent sections of the switch-board, the multiple jacks being multiplied to the several sections of the switch-board, which grouping arrangement or any other preferred grouping is well understood.

In the embodiment of the invention shown, the line relays 11 have their windings desirably permanently associated with the corresponding lines and the common battery 12, this battery being desirably interposed between two fractions of the line relay winding, which fractional windings are preferably of unequal resistance, as will appear.

When a subscriber removes his telephone, the line relay 11 becomes energized, whereby a circuit through the line signal device 13 corresponding to the calling subscriber, is completed, owing to the closure of the line relay switch 1 1, which becomes included in a local circuit that contains the battery 12, the signal 13, preferably a small incandescent lamp, the unattracted armature of a cut-off relay 15 and the armature 141 with its alternate contact. A slight resistance 16 is also included in this local circuit, there being one such resistance to each line for the purpose of the busy test. This resistance may be of twenty ohms, for example, and its purpose will more clearly appear later. The operator, in responding to the signal displayed by the device 13, inserts an answering plug 1.7 into the jack of the calling subscriber in order to ascertain the wants of the subscriber,for which purpose she brings her telephone set 18 into telephonic connection with the calling subscriber by apparatus so well understood as torequire no description. The answering plug 17 (as also preferably the connecting plug 18) is provided with tip and sleeve contacts shown for engagement with the contacts 10 and 9, respectively, and a body contact 19 forconnection with a metallic jack thimble 20, the jack thimbles belonging to the same group of multiple jacks being electrically connected. The tip contacts of each cord circuit are telephonically united, as are also the sleeve contacts. The body contacts of the said plugs have direct electrical connection with one pole of the battery 12.

There are preferably two supervisory or disconnect signals in association with each cord circuit, as indicated at 21, 22, the device 21, preferably a small incandescent lamp, constituting the calling subscribers supervisory or disconnect signal, while the device 22, also preferably a small incandescent lamp, also constitutes the calledsubscriberssupervisory or disconnect signal. A pilot disconnect signal device has a winding 23 desirably in circuit and preferably common to a plurality of calling subscribers supervisory or disconnect signal circuits, the winding 23, in the embodiment of the invention shown, constituting a part of an electromagnet or relay which occasions the continuity of a local circuit 24 containing the pilot lamp 25. The operator having plugged into the jack of a calling subscriber, brings the cut-off relayinto such circuit relation with the line that it is included in series with the calling subscribers switch-hook, the circuit containing said cut-off relay also including registering contacts of the plug and jack. The circuit of this cut-off relay desirably in cludes the tip and sleeve contacts of the engaged plug and the corresponding springs or contacts of the jack into which said plug is inserted, and a conductor 26 including impedance 27 and uniting the said tip and sleeve contacts of the plug. It should be stated in passing that the connections and circuit relations of the connecting plug are similar to those of the answering plug.

As the cut-off relay is in series with the switch-hook of the corresponding telephone line (be it a calling or called line) and is also in series with registering contacts of the corresponding jack and plug, it will be seen that the operator and subscriber have to cooperate in order to energize the cut-off relay. That portion of the relay circuit containing the cut-off relay winding and the impedance 27, is included in parallel with one of the two parts of the winding of relay 11, which part may also the impedance device 27,

may, for example, have a resistance of two hundred ohms while the cut-off relay may have a resistance of one hundred ohms, as The part of the relay 11 companion to the aforesaid part, may have a resistance of one hundred ohms. Assuming some such values as those that have been chosen as example, when an operator effects connection with a line, the battery 12 has connection with the line through effective resistances that are balanced. The condenser 28 is included in a talking side of each telephone line so as to maintain the line signal circuits and the clearing-out signal circuits separate or distinct and so as to maintain the line signal circuits and the cut-off relay circuits distinct.

The operator having effected connection between a cord circuit and a line closed at its sub-station, by the removal of the telephone from the switch-hook at said substation, causes the operation of the corresponding cut-oil relay 15 to remove the line signal 13 from circuit. This line signal cannot be reassociated with the telephone line by opening the linecircuit at the sub-station, because the armature switch 14 would be released by such action.

I will now describe that feature of my invention relating to the test.

It will be seen that the thimbles 20 are normally charged with current from the battery 12 by way of the normally unattracted armature switch 14 corresponding thereto and the resistance 16. An operators test coil or device 29 is connected with her receiver and the tip strand of the testing plug, assuming that the listening key is depressed. This testing device 29 is connected with the same grounded terminal of the battery 12 with which the rings 20 are normally connected, so that an operator testing an idle line, hears no noise. This condition is not changed when a subscriber first initiates a call, forthe attraction of the armature switch 14 removes all battery. As soon, however, as any plug, be it an answering or a connecting plug, is inserted in a thimble 20, the other terminal of the battery 12 is connected with the rings 20 in circuit with the body contact of the inserted plug, whereby said thimbles are now so connected with the battery that a noise will be manifest when any testing plug contact is applied to one of said thimbles.

As illustrated in the preferred embodiment of the invention, the line signal device ineludes an operating relay 11 controlling a switch included in a local circuit containing a signal lamp or other signal presenting device, but I-do not wish to be limited to this precise arrangement.

While I have indicated stations A, B as or dinary subscribers stations and the switches 4 thereat as ordinary telephone switch-hooks,

I do not Wish to be limited to the adaptation of my invention to subscribers stations, nor to the use of switch-hooks in practicing the invention.

An important feature of my present inven tion resides in the circuit control of the clear ing-out or supervisory signals. It will be observed that the armature switches 14 of the line relays open the supervisory or disconnect signal circuits when said armature switches are attracted by said relays, and that these circuits are closed when said armature switches are released, whereby the bat tery is only brought into service when the supervisory or disconnect signals are to appear.

It will be observed that the supervisory or disconnect signals 21, 22 are included in local circuits that contain jack and cord circuit conductors which are in a part of the telephonic circuits, and that the control of these supervisory or disconnect signals is jointly effected by the registering contacts of plugs and jacks and means, preferably the line relays, and permanently associated with the lines.

It is obvious that many changes may be made in the system of my invention, without departing from the spirit otthe invention, and I do not, therefore, wish to be limited to the precise system shown and described, but,

Having thus described my invention, I claim as new and desire to secure by Letters- Patent the following z- 1. A telephone exchange system including a plurality of telephone lines extending to an exchange, connecting means for uniting lines in conversation, line relays for said lines, each having two winding portions, a battery connected between the winding portions of each line relay, cut-oil relays, each having a circuit connection adapted to be included in parallel with one of the winding portions of a line relay by said connecting means, and condensers in talking sides of the telephone lines serving to separate circuits of the cut oil" and line relays.

2. A telephone exchange system including a plurality of telephone lines extending to an exchange, connecting means for uniting tele phone lines in conversation, line signal circuits, each including an electro-magnet having two winding portions, a battery connected between the winding portions of each electro-magnet, cut-oil? relays, each havinga circuit connection adapted to be included in parallel with one of the winding portions of an electro-magnet by said connecting means, and condensers in talking sides of the tele phone lines serving to separate line signal and cut-oil relay circuits.

3. A telephone exchange system including a plurality of telephone lines extending to an exchange, connecting means for uniting lines in conversation, line relays for said lines,

each having two winding portions, a battery connected between the winding portions of each line relay, cut-off relays, each having a circuit connection adapted to be included in parallel with one of the winding portions of a line relay by said connecting means, and condensers in talking sides of the telephone lines serving to separate circuits of the cutoil and line relays, said circuit connection including an impedance winding adapted to be connected in bridge of a telephonic circuit extending between subscribers stations.

4. A telephone exchange system including a plurality of telephone lines extending to an exchange, connecting means for uniting telephone lines in conversation, line signal circuits, each including an electro-magnet hav ing two winding portions, a battery connected between the winding portions of each electro-magnet, cut-off relays, each having a circuit connection adapted to be included in parallel with one of the winding portions of an electro-magnet by said connecting means, and condensers in talking sides of the telephone lines serving to separate line signal and cut-off relay circuits, said circuit connection including an impedance winding adapted to be connected in bridge of a telephonic circuit extending between subscribers stations.

5. A telephone exchange system including a plurality of telephone lines extending to an exchange, connecting means for uniting lines in conversation, line relays for said lines, each having two winding portions, a battery connected between the winding portions of each line relay, cutoil' relays, each having a 'circuit connection adapted to be included in parallel with one of the winding portions of a line relay by said connecting means, and condensers in talking sides of the telephone lines serving to separate circuits of the cut-off and line relays, said circuit connection including an impedance winding connected between the sides of the cord circuit.

6. A telephone exchange system including a plurality of telephone lines extending to an exchange, connecting means for uniting telephone lines in conversation, line signal circuits, each including an electro-magnet having two winding portions, a battery connected between the winding portions of each electro-magnet, cut-oil relays, each having a circuit connection adapted to be included in parallel with one of the winding portions of an electro-magnet by said connecting means, and condensers in talking sides of the telephone lines serving to separate line signal and cut-oil relay circuits, said circuit connection including an impedance winding connected between the sides of the cord circuit.

7. A telephone exchange system including a plurality of telephone lines extending to an exchange, connecting means in the form of a cord circuit for uniting lines in conversation, line relays for said lines, each having two winding portions, a battery connected between the winding portions of each line relay, cut-off relays, each having a circuit connec tion adapted to be included in parallel with one of the winding portions of a line relay by said connecting means, and condensers in talking sides of the telephone lines serving to separate circuits of the cut-off and line relays, said circuit connection including an impedance winding connected between the sides of the cord circuit.

8. A telephone exchange system including a plurality of telephone lines extending to an exchange, connecting means in the form of a cord circuit for uniting telephone lines in conversation, line signal circuits, each including an electro-magnet having two winding portions, a'battery connected between the winding portions of each electro-magnet, cut-oil relays, each having a circuit connection adapted to be included in parallel with one of the winding portions of an electro magnet by said connecting means, .and condensers in talking sides of the telephone lines serving to separate line signal and cut-off relay circuits, said circuit connection including an impedance winding connected between the sides of the cord circuit.

9. A telephone exchange system including a plurality of telephone lines extending to an exchange, connecting means for uniting lines in conversation, line relays for said lines, each having two winding portions, a battery connected between the winding portions of each line relay, cut-ofl' relays adapted to be included by said connecting means in serial relation with said battery, one of said winding portions and the telephone line, and in parallel with the other winding portion, and condensers in talking sides of said telephone lines serving to separate said line signal and cut-off relay circuits.

10. A telephone exchange system including a plurality of telephone lines extending to an exchange, connecting means for uniting lines in conversation, line signal circuits, each including an electro-magnet having two winding portions, a battery connected be* tween the winding portions of each line relay, cut-off relays adapted to be included by said connecting means in serial relation with said battery, one of said winding portions and the telephone line, and in parallel with the other winding portion, and condensers in talking sides of said telephone lines serving to separate said line signal and cut-ofi' relay circuits.

11. A telephone exchange system including a plurality of telephone lines extending to an exchange, connecting means for uniting lines in conversation, line relays for said lines, each having two winding portions, a battery connected between the winding portions of each line relay, electro-magnetic devices, each adapted to be included by said connecting means in serial relation with said battery, one of said winding portions and the telephone line, and in parallel with the other winding portion, and condensers in talking sides of said telephone lines serving to separate said line signal and electro-magnetic device circuits.

12. A telephone exchange system including a plurality of telephone lines extending to an exchange, connectingmeans for uniting lines in conversation, line signal circuits, each including an electro-magnet having two winding portions, a battery connected between the winding portions of each line relay, electro-magnetic devices, each adapted to be included by said connecting means in serial relation with said battery, one of said winding portions and the telephone line, and in parallel with the other winding portion, and condensers in talking sides of said telephone lines serving to separate said line signal and electro-magnetic device circuits.

In witness whereof, I hereunto subscribe my name this 26th day of September A. D. 1906.

ELMER R. CORWIN.

Witnesses:

G. L. CRAGG, LEON G. STROH. 

